Liquid extraction apparatus



Oct. 9, 1962 M. w. DAVIDSON LIQUID EXTRACTION APPARATUS Filed July 1, 1959 '7 Sheets-Sheet 1 EQW Oct. 9, 1962 M. w. DAVIDSON LIQUID EXTRACTION APPARATUS 7 Sheets-Sheet 2 Filed July 1, 1959 Oct. 9, 1962 M. w. DAVIDSON I LIQUID EXTRACTION APPARATUS Filed July 1, 1959 7 Sheets-Sheet 3 I m F ZZZ {WM/M M mmmo0 1 Oct. 9, 1962 Filed July 1, 1959 M. W. DAVIDSON LIQUID EXTRACTION APPARATUS 7 Sheets-Sheet 4 Oct. 9, 1962 Filed July 1, 1959 I M. W. DAVIDSON LIQUID EXTRACTION APPARATUS 7 Sheets-Sheet 5 Oct. 9, 1962 M. w. DAVIDSON LIQUID EXTRACTION APPARATUS 7 Sheets-Sheet 6 Filed July 1, 1959 Oct. 9, 1962 M. w. DAVIDSON 3,057,290

LIQUID EXTRACTION APPARATUS Filed July 1, 1959 7 Sheets-Sheet 7 United States Patent ()fiice 3,057,290 Patented Oct. 9, 1962 3,057,290 LIQUID EXTRACTION APPARATUS Maxwell Wingate Davidson, Galashiels, Scotland, assignor of one-half to Sanderson & Murray, Limited, Galashiels, Scotland, a British company Filed July 1, 1959, Ser. No. 824,393 Claims priority, application Great Britain July 5, 1958 7 Claims. (Cl. 100211) This invention relates to apparatus for extracting liquids from materials examples of which are fibrous textile materials, such as wool and cotton, textile articles, such as piece goods, knitted fabrics, garments and yarn, fibrous or granular materials, such as peat, moss litters, slurries and chemical wastes and vegetable materials, such as processed potatoes, mashed vegetables, and pulped fruit.

In the specification of my prior patent application Serial No. 616,179, issued as Patent No. 2,931,290 on April 5, 1960, there is described a press for extracting liquids from materials, including a rigid frame, a flexible bag inflatable by pressure fluid and suspended from the frame, and an orificed plate or screen located below and vertically spaced from the frame, the bag being adapted to press material from which liquid is to be extracted towards the plate or the screen.

While the press of my prior application is satisfactory for extracting liquids from most of the materials listed above, it is diflicult satisfactorily to extract liquids from materials, such as slurries, which are fluid or semi-fluid and the flow of which requires to be restrained before operation of the press to apply the flexible bag to the material.

The primary object of the present invention is to provide for eflicient extraction of liquids from materials having a high liquid content.

In apparatus according to the invention including a rigid frame, a flexible bag suspended from the frame inflatable by pressure medium, and a screen located below and vertically spaced from the frame, an endless conveyor including a filter cloth having an upper horizontal flight passing above the screen and below the bag, a sealing member of closed geometrical form adapted to abut on the upper face of the screen suspended from the frame below the bag and operatively connected to means for effecting vertical movement of said sealing member and means for trapping material from which liquid is to be extracted in the space defined by the sealing member.

Apparatus according to the invention is illustrated in the accompanying drawings in which:

FIGS. 1, 1A and 1B constitute, collectively, a side elevation of the apparatus;

FIGS. 2 and 2A constitute, collectively, an end view of the apparatus taken from the left of FIGS. 1 and 1A;

FIG. 3 is a plan view of a sealing member, drawn to a smaller scale than the preceding figures;

FIG. 4 is an end elevation of the sealing member;

FIG. 5 is a section on the line 55 of FIG. 3;

'FIG. 6 is a plan view of a screen, drawn to the same scale as FIG. 3;

FIG. 7 is a plan View of a tank incorporated in the apparatus; and

FIG. 8 is a section on an irregular line generally represented by the line 88 of FIG. 7.

Referring to the drawings in which some of the parts are shown diagrammatically, 10 denotes a flexible bag in the form of a bellows inflatable by pressure medium and suspended from a rigid frame 11. 12 (FIGS. 2, 2A and 6) denotes a screen supported by a rigid frame 13 complementary to and vertically spaced from the frame 11. The bellows 10 is sustained in engagement with the underface of the frame 11 by means of tension springs 10 each of which is connected at its upper end to the frame 11 and at its lower end to the frame of the bellows 10.

An endless conveyor constituted by an endless band 14 of lightweight filter cloth secured between chains 15 trained around sprockets 16 is so arranged to travel around the frame 13 as to present an upper horizontal flight passing above the screen 12 and below the bag 10.

A metallic sealing ring 17 adapted to abut on the upper face of the screen 12 is suspended from the frame 11 below the bag 10 and is arranged to move vertically. The screen 12 is bounded by a metallic ring 18 which corresponds to the sealing ring 17 and houses the mesh of the screen 12 proper.

Where the material to be treated is of the consistency of porridge and is not liable to adhere to other materials, we may provide a bag (not illustrated) of lightweight filter cloth the peripheral edge portion of which is secured to the sealing ring 17 in such wise as to trap the material.

Where the material is fluid or semi-fluid as, for example, a slurry, or is liable to adhere to other materials, we provide (as illustrated) an endless conveyor constituted by a band of lightweight filter cloth 19 so secured between chains 20 trained around sprockets 21 as to travel around the frame 11 and between the screen 12 and the sealing ring 17, the cloth 19 being secured to the chains 20 in a slack condition.

Two opposed parts of the sealing ring 17 are each connected to the piston rod 22 of a piston vertically movable in a double-acting piston and cylinder assembly 23 operable by pressure medium and mounted on the frame 11, as shown in FIGS. 1A, 1B, 3 and 4.

The inner edge portion of the sealing ring 17 is bevelled at 24 (FIGS. 3 and 5) to permit the bag 10, when inflated, to enter the ring 17 in such wise that all the material trapped in the space defined by the sealing ring 17 is contacted by the inflated bag 10.

The sealing ring 17, as shown in FIG. 5, consists of a rigid ring, a toroidal ring 25 of resilient material fitted to the underface of the rigid ring, and a ring 26 of sponge rubber surrounding the toroidal ring 25 and fitted to the underface of the rigid ring.

One may interpose between the bag 10 and the sealing ring 17 a flexible sheet (not illustrated) the underface of which is formed with a plurality of equi-spaced ridges of V-section extending transversely of the path of movement of the adjacent flights of the filter cloth bands 14, 19.

To provide for extraction of liquid from a fluid or a semi-fluid material, a tank 27 is provided for reception of the material. A duct 28 leads from a discharge outlet in the tank 27 to a flexible nozzle 29 mounted in the apparatus for insertion into and discharge of material to the space defined by the sealing ring 17. Admission and discharge of material to and from the tank is controlled by an upper float 30 and a lower float 31 (FIGS. 2, 2A, 7 and 8). The lower float 31 (FIG. 8) controls admission of material to the tank 27 by way of a non-return valve 32; and the upper float 30 controls admission to the tank of compressed air for discharge of material from the tank 27.

At the discharge end of the apparatus, as shown in FIG. 1B, a brush 33 is mounted in a bracket 34 on the frame 13 for rotation about a horizontal axis against the cloth 14 of the lower conveyor, and a brush 35 is mounted in a bracket 36 on the frame 11 for rotation about a horizontal axis against the upper cloth 19. A bracket 37 is adjustably mounted on the frame 11 for tensioning the part of the filter cloth 19 in contact with the brush 35. Both brushes 33, 35 serve to remove material which may be adhering to the filter cloths 14, 19. Means (not illustrated) such as Water or steam sprays, or nozzles for 3 flow of air under pressure, may be located adjacent to the inner face of the return bend of each cloth 14, 19 at the discharge end of the apparatus, whereby further to clean the cloths. Where water or steam sprays are provided, a trough is provided for collection of the washed material.

In practice, material from which liquid is to be extracted is pumped into the tank 27 by way of the nonreturn inlet valve 32 until the valve 32 is closed by the float 31 after the level of material in the tank 27 is set at a predetermined height. Travel of the filter cloths 14, 19 below the bag is stopped and the pressure medium is withdrawn from the piston and cylinder assemblies 23 to permit the sealing ring 17 to descend under the influence of gravity to a position in which the ring 17 rests on the screen 12 with the filter cloths 14, 19 superposed one on top of the other and gripped lightly between the ring 17 and the screen 12. The flexible nozzle 29 extends between the filter cloths 14 and 19 into the area defined by the sealing ring 17.

Air under pressure is admitted through a valve to the tank 27 to displace the material which flows through the discharge duct 28 and the nozzle 29 which expands slightly to allow the liquid-containing material to debouch into the space between those parts of the filter cloths 14, 19 gripped between the sealing ring 17 and the screen 12; the upper cloth 19, being slack, rises up and forms an envelope enclosing the material .discharged from the tank 27. After the desired quantity of material has been discharged from the tank 27, the lower float 31 in the tank 27 is arranged to actuate the inlet valve 32 to open to permit the admission of material to the tank 27 and float closes the air Valve.

During filling of the envelope defined by the upper filter cloth 19, the weight of the rigid part of the sealing ring 17 is suflicient to prevent leakage tom the nozzle 29, but is not sufficient to prevent the flow of liquid-containing material into the envelope defined by the filter cloth 19 within the space defined by the sealing ring 17, the sponge rubber ring 26 being compressed sufiiciently to maintain a seal against leakage of material provided that the static head of material filling the envelope does not exceed six inch water gauge.

Pressure medium is then admitted to the piston and cylinder assemblies 23 to actuate the pistons in the direction to cause the sponge rubber ring 26 to be compressed until the toroidal ring 25 contacts the upper filter cloth 19 and seals said cloth 19 firmly against the lower filter cloth 14.

The bag 10 is then inflated and presses the flexible sheet, where a flexible sheet is provided, against the envelope formed by the upper filter cloth 19. Fluid pressure in the bag acting laterally on the unsupported side of the bag has the eifect of tensioning uniformly the surface of the bag in contact with the material, which surface, being in tension, conforms readily to the configuration of the material. Liquid extracted from the material flows through the lower filter cloth 14 and the screen 12 to a drain and through the upper filter cloth 19 into the grooves between the ridges of the flexible sheet and thence to the drain.

The bag 10 is then deflated and the sealing ring 17 is caused to rise by actuation of the associated piston and cylinder assemblies 23. The driving means for the conveyors is then operated to cause the conveyors to convey the material from which liquid has been extracted to the discharge end of the apparatus. The above-described operation is then repeated with a fresh batch of material.

It is to be understood that the cycle of operations of the apparatus may be controlled automatically and that operation of the assemblies 23 is etfected in synchronism with inflation and deflation of the bag 10-.

What is claimed is:

1. An apparatus for extracting liquid from fluid or semi-fluid slurry type materials, including a rigid frame, a flexible inflatable and deflatable bag suspended from said frame, a screen located below and vertically spaced from said frame, an endless conveyor including a filter cloth having an upper horizontal flight passing above said screen and below said bag, a sealing ring of closed geometrical form suspended from the frame below and independent of the bag and above the filter cloth of the conveyor directly over said screen, said sealing ring being mounted for vertical movement relative to the frame and when lowered onto said filter cloth presses the filter cloth against the screen and therewith defines a space in which is trapped material from which liquid is to be extracted, and means for delivering slurry-type material to be extracted directly into said space, said bag being disposed above said ring and on inflation being in position to seat within said ring and press the liquid content of the material from the material within the space defined by the sealing ring, the filter cloth and the bag.

2. Apparatus as claimed in claim 1, including a second endless conveyor provided with a filter cloth having a horizontal flight passing above the horizontal flight of the first-mentioned conveyor and below said sealing ring and said bag, the filter cloth of the horizontal flight of said second conveyor being in a slack condition.

3. Apparatus as claimed in claim 1, in which the screen includes and is bounded by a rigid frame of closed geometrical form corresponding to that of the sealing ring.

4. Apparatus as claimed in claim 1, including a pair of spaced double-acting piston and cylinder assemblies mounted on the frame and operable by pressure fluid for effecting vertical movement of the sealing ring, each assembly including a vertically movable piston and piston rod, the piston rods of the assemblies being connected respectively to two opposed parts of the sealing ring.

5. Apparatus as claimed in claim 1 in which the sealing ring has a beveled inner edge portion to permit the bag, when inflated, to enter the ring in such wise that all the material trapped in the space defined by said ring is contacted by said bag.

6. Apparatus as claimed in claim 1 in which the sealing ring is a rigid ring, a toroidal ring of resilient material fitted to the underface of said sealing ring, and a ring of resilient material fitted to the underface of said sealing ring and encircling the toroidal ring.

7. Apparatus as claimed in claim 1 including a tank for reception of material to be treated, means for controlling the admission of material to said tank, and means for discharging material from said tank through a flexible nozzle leading to the space .defined by the sealing ring, the filter cloth and the screen.

References Cited in the file of this patent UNITED STATES PATENTS 602,620 Flory Apr. 19, 1898 1,738,326 Smith Dec. 3, 1929 2,135,763 Nicholson Nov. 8, 1938 2,575,734 Schulman Nov. 20, 1951 FOREIGN PATENTS 18,815 Sweden Jan. 21, 1903 29,353 Sweden Sept. 19, 1907 520,254 Germany Mar. 1, 1928 649,837 Germany Sept. 6, 1937 

